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A variable is something that can change. There are three kinds of variables . . . Independent Variable This is the variable you are testing, or manipulating. In your first experiment, where you are deciding if the liquid has to be hot, you would try the experiment with hot liquid, and then again with cold liquid. The independent variable here is the temperature. We want to know if, by changing the temperature, we would see a change in the sound behavior. Dependent Variable This is the variable you are measuring, or observing. In this case, we are observing the behavior of the sound increasing in pitch. Does changing the temperature make the sound behave differently? Controlled Variables If the sound behaviour does change if we try cold coffee, we want to make sure that it was the different temperature that made the sound behaviour change, and not something else. So we would make sure everything else syays the same. Other variables that might change the result are kept the same, or 'controlled'. For eample, when we try the experiment with cold liquid, we don't wat to switch to water. Then we won't know whether it was the cold temperature that caused the sound behaviour to change, or the fact that we used water. So we'll control the variable 'type of liquid' by keeping it the same. Some of the variables you might want to control in this first experment would be: - The type of liquid - The amount of liquid - The amount of milk - The type of spoon and cup - The force you tap with - The number of taps. |